1. Field of the Invention
The present invention relates to power supplies, and particularly to an electronic device and its power supply unit.
2. Description of Related Art
Electronic devices such as notebook computers, cellular phones, digital video disk player/recorders, etc are now very popular. Referring to FIG. 3, a typical electronic device 10 includes a power supply unit 100 and an operating unit 150. The power supply unit 100 is configured for receiving power from an external power supply (not shown), and powering the operating unit 150 (load). The external power supply may be an external alternating current (AC) adapter, or a battery unit. The operating unit 150 is a main function unit of the electronic device 10. The operating unit 150 may include a central processing unit, a storage unit, a display unit, etc.
The power supply unit 100 includes a power supply interface 102, a first convertor 104, a controller 106, and a second convertor 108. The power supply interface 102 receives a first direct current (DC) voltage from the external power supply, and conducts/transmits the first DC voltage to the first convertor 104 and the second convertor 108. The first convertor 104 converts the first DC voltage into a second DC voltage to power the controller 106. The controller 106 is connected to the operating unit 150 and to the first and second convertor 104, 108. The controller 106 is used for communicating with the operating unit 150 (detecting operating parameters of the operating unit 150, for example), and managing the power supply of the electronic device 10. In detail, the controller 106 enables the second convertor 108 when receiving the second DC voltage. The second convertor 108 receives the first DC voltage and powers the operating unit 150 when enabled. However, a disadvantage of the power supply unit 100 is that the first convertor 104 still works to supply the second DC voltage to the controller 106 when the second convertor 108 powers the operating unit 150. This inefficiently consumes power of the electronic device 10.
Therefore, an improved electronic device and its power supply unit are needed to address the aforementioned deficiency and inadequacies.